Features are simple options (true/false), and are stored in the global configuration array $TYPO3_CONF_VARS[SYS][features].

For disabling or enabling a feature the "ConfigurationManager" should be used.

-- Naming --

Feature names should NEVER be named "enable" or have a negation, or contain versions or years "enableFeatureXyz" "disableOverlays" "schedulerRevamped" "useDoctrineQueries" "disablePreparedStatements" "disableHooksInFE"

Proper namings for features "ExtendedRichtextFormat" "NativeYamlParser" "InlinePageTranslations" "TypoScriptParserIncludesAsXml" "NativeDoctrineQueries"

Ideally, these feature switches are added via the Install Tool or via FactoryConfiguration and can be used for Extensions as well.

--- Usage ---

if (GeneralUtility::makeInstance(Features::class)->isFeatureEnabled('InlineSvg')) { ... do stuff here ... }